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United States Patent | 6,029,648 |
Willis | February 29, 2000 |
A natural draft furnace has a firebox inside a water box with fire tubes containing water running through the firebox, flues from the firebox running through the water box, a front/fire door of double wall construction to preheat entering air, a damper in the fire door and a toggle-lock latching system on the fire door that provides uniform sealing pressure around the door.
Inventors: | Willis; W. Coy (Apollo Engineering, 22161 Stipps Hill Rd., Laurel, IN 47024) |
Appl. No.: | 995143 |
Filed: | December 29, 1997 |
Current U.S. Class: | 126/101; 110/173R; 110/175R; 122/498; 126/197; 126/285R; 236/99R |
Intern'l Class: | F24D 009/00; F23M 007/00; F23M 007/04; G05D 023/12 |
Field of Search: | 126/101,293,197,285 R,190 122/15,498 110/173 R,174,176,178,175 R 236/99 R,99 F,99 H |
1989105 | Jan., 1935 | Miles | 236/99. |
3599865 | Aug., 1971 | Kristiansen | 236/99. |
3976245 | Aug., 1976 | Cole | 236/93. |
4145259 | Mar., 1979 | Leumann | 202/248. |
4360152 | Nov., 1982 | Schlatter et al. | 237/13. |
4383519 | May., 1983 | Katona | 126/190. |
4418649 | Dec., 1983 | Purvis | 122/15. |
4461242 | Jul., 1984 | Black | 122/15. |
4461243 | Jul., 1984 | Carpaneto | 122/15. |
4479605 | Oct., 1984 | Billotte et al. | 237/8. |
4497262 | Feb., 1985 | Nordine | 110/234. |
4612878 | Sep., 1986 | Schnurer | 122/15. |
4724798 | Feb., 1988 | Alspaugh | 122/15. |
4779795 | Oct., 1988 | Winmill | 237/51. |
5329920 | Jul., 1994 | Brazier | 126/344. |
5377661 | Jan., 1995 | Farver | 126/101. |